Method and apparatus for the administration of gases



March 9, 1937. K. CONNELL 2,073,192.

METHOD AND APPARATUS FOR THE ADMINISTRATION OF GASES Filed Oct. 21, 1931I VENTOR 4-24, Z/ BY ATTORNEY @etentet] Q, 337

UNHTEL) Z WBAQZ ()FFHQE acrea e METHQD AND APPARATUS EG'Fs 'LJHIEADMIINKSTRATHUN (F GASES 28 Claims.

This invention relates to a method and means for administering gases andmore particularly to a method of gas delivery for anaesthesia and othertherapeutic purposes. I

In general, it is an object of this invention to provide a safeeconomical method of gas delivery and apparatus for use in connectiontherewith, which is simple of construction and inexpensive tomanufacture, which can be expeditiously and conveniently manipulated,and which will efficiently perform the purposes for which it isintended.

Another object is to provide apparatus which will effectively utilizesubstantially all of the fresh gas delivered.

Another object is to provide apparatus which will give controlledextrusion of used gases and products of metabolism.

Another object is to provide apparatus adapted to prevent explosion ofcombustible vapors used in gaseous therapeusis.

Another object is to provide apparatus adapted to deliver fresh gas tothe patient at the beginning of the breathing cycle and redeliverexhaled gas thereafter, whereby the fresh gas is carried to the alveolarpassages.

Another object is to provide apparatus which receives a constant inputof fresh gas and which feeds a substantial portion of said gas stillfresh to the patient, and which also at some period of the breathingcycle feeds the patient gas previously exhaled.

Another object is to provide apparatus adapted to guide fresh gas duringa portion of the breathing cycle directly to the respiratory tracts.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationand order of one or more of such steps with respect to each of theothers, and the apparatus embodying features of construction,combinations of elements and arrangement of parts which are adapted toeffect such steps, all as exemplified in the following detaileddisclosure, and the scope of the application of which will be indicatedin the claims.

For a fuller understanding of the nature and objects of the inventionreference should be had to the following detailed description taken inconnection with the accompanying drawing, in

(Cl. 128-2il3) Fig. 2 is a detailed view in elevation and partly insection of the pressure control means shown in Fig. 1;

Fig. 3 is a detailed view in elevation and partly in section of thewater supply means shown in Fig. 1;

Fig. 4 is a view in elevation of a modification of a portion of theapparatus shown in Fig. 1;

Fig. 5 is a, view similar to Fig. 4 showing the valve in position foraffording communication between the mask and the air and showing thevalve handle; and

Fig. 6 is a view similar to a portion of Fig. 1 showing a slightlymodified construction.

The average human adult breathes ineach cycle a certain normal volume ofair which is known as tidal air. At rest the tidal air is about 200 c.c. The normal rate of breathing is from 12 to 18 cycles per minute andthe normal total exchange of air is from 4,000 to 6,000 c. 0. per 0minute. Under the excitation of an anaesthesia and the stimulation ofretained carbon dioxide, the rate may rise to or more per minute and thetidal volume to 300 c. c., or, on occasional unusual effort, to 1200 c.c. 25

In anaesthetic practice where the patient is caused to rebreathe exhaledair it is necessary to add a certain quantity of fresh gas200 c. c. ofoxygen per minute to replace oxygen actually consumed and needed tosupply the vital needs, 400 c. e. per minute to maintain sufficientpressure to cause the diffusion of the gases to the far alveolar lungpassages, and a proper quantity of anaesthetic gases and vapors tomaintain the required anaesthetic pressure in the blood. Furthermore,there must be an excess for washing out of the breathing system theproducts of metabolism so that the vapor pressure of the carbon dioxidein the alveolar air may be but about mm. of mercury. An amount of gasmay constantly be spilled, i. e., discarded, equivalent to the addedfresh gas. It is economically of importance that the spilled gas shouldbe the used exhaled gas and that it should contain substantially none ofthe fresh gas. It is also of importance both economically andphysiologically that the fresh gas enter directly into the deflated lungand substantially unmixed with gas previously exhaled. The more proximalto the patient the delivery of fresh gas is into the apparatus, the lessintermlngling there will be with the expired gas and the more effectivethe operation of the device. Under special conditions it may benecessary to deliver the fresh gas directly by intubation into thebifurcation of the trachea and thus avoid using the fresh gas to fillthe 140 c. c. of dead air space in the upper respiratory tract. Itusually suffices, however, to deliver the fresh gas I into a maskadjacent to the nares.

This invention contemplates a tube for fresh gas leading into such amask and a conduit for expired gas leading away from the mask. The

conduit may have suflioient capaeity to contain not only a normal, butalso an excessive, tidal volume. It is possible to lead the tubedirectly into the conduit proximal to the patient and to insert theconduit into the respiratory tract. A construction of this type is shownin Fig. 6 wherein the tube lit for fresh gas leads directly to theconduit 9 do. for expired gas and the conduit is introduced into themouth of the patient. The breathing cycle is normally carried out inthree periods-the inspiration, the expiration and a quiet period. Duringthe quiet period the fresh gas pushes the expired gas out of the maskand to some extent distally from. the patient along the conduit. Theexcess, much rebreathed gas in the distal, i. e., far, end of conduitthereby is spilled from the conduit. Upon inspiration the fresh gaspasses deep into the lungs and penetrates the alveolar passages, whereit is immediately available to the blood stream. The previously-expiredgas is drawn in next in succession, having a slight intermixture of thecontinuouslysupplied fresh gas, and fills the remaining portions of therespiratory passages. During expiration some of the fresh gas mixes withthe expired gas as it passes out of the mask and into the conduit. Onlya relatively small fraction of this fresh gas is lost going into thatportion of the expired gas which does not return to'the patient. On athree-liter flow of fresh gas to a patient breathing nine liters perminute in such a closed breath- 40 ing system, this total loss is butone-ninth of the fresh gas on the average.

It may be observed in this connection that it is desirable to change thecharacter of the fresh gas introduced from time to time during theanaesthetic treatment.

The cross-section of the conduit should not be too small to permit easybreathing by the patient. If, however, the cross-section is too large,the rear end of the expired gas which is being 59 pushed along theconduit by the fresh gas during the quiet period presents a large areato that fresh gas with the result that the latter is contaminated by theformer, due not only to simple difi'usion but also to the eddying setup.

Under certain conditions apositive pressure may be advantageous and adistensible reservoir, preferably a bag, may be attached to the distalend of the conduit, in which case the conduit need not be as long aswould otherwise be desirfi able to prevent outside air from beingbreathed by the patient under extraordinary conditions.

The actual spill device may control the ingress of atmospheric air.

Preferably'the conduit itself provides a sum- 85 cient capacity to takecare of the usual tidal Volumes.

In accordance with the invention, conduits having a capacity of from 100c. c. to 2,000 c. c.

70 may be provided, thereby providing for the reception of fresh gasduring the time between exhalation and inhalation and for the inhalationof used gas during the latter part of the inhalation period, but aminimum volume of from 200 to 300 c. c. is preferable.

In apparatus using anaesthetizing and other gases through rubber tubing,there is a small, but in many cases, almost prohibitive danger ofexplosion of the gasdue to heat conditions or to the sparking as aresult of the electric charges induced by friction of the gas or bysmall particles of solid matter carried thereby against the dielectricwalls of the tube, or due to differences in potential of metallic partsat difierent portions of the dielectric conduit. There is also a dangerin a wide variety of operation of combustion or explosion of combustibleor explosive gases due to various causes including the proximity ofelectric charges, of hot metal, or of flame. Gaseous anaesthesia employsnitrous oxide, ethylene, and other gases and vapors together withoxygen. Certain of these combinations, especially mixtures of ethyleneand acetylene in oxygen are highly explosive. Mixtures of from 5 to 45%of gaseous hydrocarbons in oxygen are particularly sensitive to smallignition sources such as minute static sparks, and are combustible from3.1% to 79.9% on sufilcient heat of ignition. The spill in the presentinvention is situated at a distance from the patient, preferably morethan 150 centimeters at a point preferably a meter above the floor andcentral to a standard which may support, beside the tube conduit, othermechanisms such as gages, humidifiers, etc. It has been found that suchan arrangement is favorable to diffusion and dilution by the surroundingair to a concentration less than the explosive limit of 3% of gaseoushydrocarbon. It has also been found that a spark must come to within"7.5centimeters of the spillway so placed or a candle flame to within 15centimeters to cause a combustion train in gases of specific gravityequal or less than air when spilling 66 c. c. a second. If the gas is aheavy sensitive anaesthetic mixture, e. g., 10% ether in oxygen flowingat 133 c. c. a second, the ignition origin must be within 10 centimetersabove, or within centimeters below, to cause ignition. Gases spilling ata distance from the patient recited above are at a safe distance fromthe electrostatically-charged attendants who may be grouped with theiroperating devices about the patient.

The mask which may be of electrically-nonconducting material such asrubber, may be provided with a conducting surface over a portion of theouter face to enable the apparatus to be electrically coupled with thepatient.

The distensible nonconducting reservoir in its action may give rise tofrictional electric charges, particularly on its inner surface. A wickleading from a water source and into said reservoir may deposit drops ofwater therein which will give a moist equipotential surface and minimizethe danger from sparking. The standard and patient may also be grounded.The fresh gas may be prehumidifled.

In the embodiment of the invention shown in the drawing the stand it isadapted to support various control members including decompression valveunits 3, flow gages i, and a pressure control valve unit ll, dials, gashumidifier unit 5, tanks 7, etc., shown generally at l l, and it maysupport the means for supplying a regulated flow of fresh gas preferablya flexible tube if to the mask exemplified conventionally, in thepresent instance, at E3. The other end of the tube communicates throughpiping 82a and the humidifier unit 6 to the flow gages which in turn areconnected by means of tubes l2b extending through a hollow upright lZcto certain of the decompressionvalves within the tube are one or moreballs all of less 3. As will be readily apparent by the regulation ofthe decompression valves in accordance with the showing of thefiow'gages, the proper gases in suitable admixture may be admitted inregulated amounts from pressure tanks l to the tube i2 in the usualmanner. The stand iii may also support the distal end of the conduit it,which is adapted to contain the tidal air. The other end of the conduitmay open into the mask it with which it may be integral. The volume maydesirably range from 200 to 1200 c. c., and preferably in a number ofcases is about 600 c. c. The conduit may be connected by conductingmeans such as piping iii to a flexible reservoir 80, which,

7 with the conduit, will give a volume of 1200 c. c.,

the tidal volume of an excessive respiratory ef-' fort. The piping itmay form a part of the stand iii. If the volume of the conduit is morethan 1200 c. c. it may open directly into the atmosphere. Thecross-section of the conduit may be from 2.8 to 12 square centimeters.

The piping it may discharge downward into and support the reservoir iii,which may be a cylindrical elastic bag, certain horizontal portionspreferably tending to have a smaller cross-section than others in themanner of a Japanese lantern. A- bag of this type gives relativelylittle friction between the parts as it changes volume. The end ita ofthe bag fits over the distal end it?) of the piping l5 and is supportedthereby.

Leading out of the piping l5, near the reservoir. and radially centralwith respect to the stand 80, is a spillway and valve unit ll, which mayinclude a pressure control which may be in the form of a tube leadinginto the atmosphere through openings 08b. The spillway may be at aheight of at least a meter above the floor. The tube i l, piping i) andbag it have no other communication with the atmosphere. The passage insaid tube is restricted at the point'iii between which point and theouter end of the tube and be multiple and divergent for more effectiveditfusion of the spillage. The tube may be rotatable about a horizontalaxis and may be associated therewith a scale it graduated to read thepressure which the balls will set up in the system corresponding to thevarious angles said tube makes with the horizontal. The greater such anangle the greater is the pressure set up. Reference may be had in thisconnection to my copending application. Serial No. 441860 filed May 1,1930. As will be apparent, the valvehnit H exerts a greater or lessrestraining pressure to counterbalance the pressure in the expansibiebag it dependent upon the inclination of the unit ll as indicated on thescale 2@. The bag it thus serves as a supplemental tidal chamber andbecause of its expansible nature will contract as the patient breathesin and will expand to a certain extent as the patient exhales, thisexpansion being controlled by the adjustment of the valve unit.

Associated with the piping i5 is a tank 2i from which means such as thewick 22 may convey water into the reservoir it. As shown, the wickpasses into the piping thence into the reservoir. The tank, piping andstand may be grounded by conductor 23.

The mask i3 is adapted to admit the fresh gas entering the mask to therespiratory tract of the patient and also to admit gas from the conduitII. The outer surface of the mask may be provided with a conductingmetallic layer 2%. The conductor 28 may couple the layer to the patientor to earth.

Valve means of any suitable type may be provided for controlling therate of flow of fresh gas delivered through tube i2.

Fig. 4 shows a modification of that portion of the apparatus where thetube it, the conduit i l and the mask come together. The housing 20.which may be metallic, has tubular projections 30 onto which the tube,the conduit and an entrance to the mask fit. The housing may be providedwith valve means 3i for connecting the interior of the housing with theatmosphere. means may comprise a bronze shoe 32 and a spring 33. As willbe seen the shoe 32 is adapted to close the gas inlet conduit when swungin a clockwise direction as by a handle M.

The above described method and apparatus is adapted to give higheiilciency through the almost complete utilization of the fresh gas, andthe exact dosage possible. It is adaptable for the administration of anygas or succession or combination of gases and may be used foranaesthesia, insufflation, super-oxygenation, resuscitation, narcoticpoisoning, carbon monoxide poisoning, respiratory collapse. asphyxia,hiccough and pneumonia therapy and the like.

Since certain changes in carrying out the above process and in theconstructions set forth which embody the invention may be made withoutdeparting from its scope, it is intended that all matter contained inthe above description or shown in the accompanying drawing shall beinterpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

Having described my invention. what I claim as new and desire to secureby Letters Patent, is: i. In apparatus of the character described, meansfor delivering, after said apparatus has begun to operate, fresh gas toa patient, means for removing gas exhaled by said patient and forre-delivering a portion oi said exhaled gas to said patient at the endof a breath, and means for building up a supply of gas in the removingmeans between an exhalation and an inhalation.

2. In apparatus of the character described. means for receiving from andre-delivering exhaled gas to a patient. means for delivering fresh gasto said patient. the first-mentioned means comprising a long narrowconduit. and means to deliver a substantial amount of said fresh gasbeing delivered to said patient substantially unmixed with said exhaledgas before said exhaled gas is re-delivered.

3. In apparatus of the character described.

-means for receiving from and re-delivering exhaled gas to a patient,and means for delivering fresh gas to said patient, a connection betweensaid delivery and receiving means, said receiving means comprising along. narrow conduit whereby a substantial amount of said fresh gas isdelivered to said patient substantially unmixed with said exhaled gasbefore said exhaled gas is re-delivered. said first mentioned meansproviding a volume equal to the tidal flow of 'a patient under theconditions described and having a cross section large enough toaccommodate said flow without undue difference in pressure,

These til) but not large enough to permit said fresh gas to mixsubstantially with said exhaled gas.

4. In apparatus of the character described, means for receiving from andre-delivering exhaled gas to a patient, and means for delivering freshgasto the said patient, the delivering means for the fresh gas, beingadapted to deliver a substantial amount of the fresh gas to the patientsubstantially unmixed with the exhaled gas before the exhaled gas isre-delivered, the means for receiving and re-delivering exhaled gascomprising a conduit having a cross-section greater than 2.9 squarecentimeters and less than 12 square centimeters, and having a capacitygreater than 200 cubic centimeters.

5. In apparatus of the character described, means for receiving from andre-delivering ex= haled gas to a patient, and means for delivering freshgas to the said patient, the means for delivering fresh gas beingadapted to deliver to the said patient a substantial amount of the freshgas substantially unmixed with the exhaled gas before the said exhaledgas is re-delivered, the means for receiving and re-delivering exhaledgas comprising a conduit having a cross-section greater than 2.9 squarecentimeters and less than 12 square centimeters, and having a length ofsubstantially not less than 150 centimeters.

6. In apparatus of the character described, a respiratory systemcomprising means for re= ceiving' from and re-delivering exhaled gas toa patient, and means for delivering fresh gas to the patient, the meansfor delivering fresh gas being adapted to deliver to the said patient asubstantial amount of the fresh gas substantially unmixed with theexhaled gas before the said exhaled gas is re-delivered, the said meansfor receiving and re-delivering exhaled gas comprising instrumentalitiesfor spilling a portion of the 40 exhaled gas from the system and adistensible reservoir connected to the said means at a point removedfrom the patient for providing tidal volume of an excessive respiratoryefiort.

7. In apparatus of the character described, a

conduit adapted for receiving from and re-delivering to a patientexpired gas, the distal end of said conduit forming an inverted U, abreathing bag opening into said end, a container on top of said invertedU.-shaped end, a liquid adapted to conduct electricity, and means forsupplying said liquid from said reservoir to the interior of said bag.

8. In apparatus of the character described,

a conduit adapted for receiving from and re= delivering to a patientexpired gas, a distensible breathing bag opening into said conduit, saidbag being accordion-shaped, and means for maintaining the electricpotential of various inner surfaces of said bag equal.

9. In a system for the administration of gases wherein fresh gas isdelivered to a patient and gas exhaled by said patient is removed,'and aportion of the exhaled gas is'redelivered from a breathing reservoir tosaid patient, the combi-- nation with a reservoir of electric-potentialequalizing means comprising a water tank and a wick extending from saidtank to said reservoir.

10. In a system for the administration of gases wherein fresh gas isdelivered to a patient and gas exhaled by said patient is removed, thepres sure of the gas which is being removed being maintained at apredetermined pressure by spilling means, and wherein a portion of theexhaled gas is redelivered from a breathing reservoir to said patient,the combination with a resenvoir of electric-potential equalizing meanscoin= .prising a water tank and a wick extending from said tank to saidreservoir.

11. A stand adapted for supporting a source of fresh gas, means fordelivering fresh gas to a, patient and means for removing gas exhaled bysaid patient and for redelivering a portion of said exhaled gas to saidpatient, said removing means having a length of substantially not lessthan 150 centimeters and having an end spilling at a point radiallycentral to said stand and at a point substantially not less thancentimeters above the hour.

12. A stand adapted for supporting a source of fresh gas, means fordelivering fresh gas to a patient and means for removing gas exhaled bysaid patient and for redelivering a, portion of said exhaled gas to saidpatient, said removing means having a length of substantially not lessthan centimeters and having an end spilling at a point radially centralto said stand and at apoint substantially not less than 100 centimetersabove the floor, a, breathing reservoir, means for equalizing theelectric potential of various parts of said reservoir, a face maskassociated with said delivering and removing means and provided withmetallic coating, electrical means adapted for coupling said coating andsaid pa= tient, and means for grounding said stand, said coating andsaid mechanism.

13. A stand adapted for supporting gas control mechanism, means fordelivering fresh gas to a patient and means for removing gas exhaled bysaid patient and for redelivering a portion of said exhaled gas to saidpatient, "said removing means having a length of substantially not lessthan 150 centimeters and having an end spilling at a point radiallycentral to said stand and'at a point substantially not less than 100centimeters above the floor, a breathing reservoir, means for equalizingthe electric potential of various parts of said reservoir, a. face maskassociated with said delivering and removing means and provided withmetallic coating, electrical means adapted for coupling said coating andsaid patient, and means for grounding said stand, said coating and saidmechanism.

14. In apparatus of the character described, means adapted for removinga tidal volume of expired gas, means adapted for adding fresh gas tosaid volume at a point adjacent the patient, means adapted formaintaining said fresh and said expired gases substantially undiifusedin said resultant volume, and means for delivering said fresh gas andthen a portion of said expired gas to the patient.

15. In apparatus of the character described, means adapted for receivinga tidal volume of expired gas and means adapted for supplying fresh gasto that portion of saidilrst mentioned means adjacent the patient, saidfirst mentioned means adapted for spilling an amount of expired gassubstantially equal to the amount of fresh gas supplied, for maintainingsaid expired gas and said fresh gas substantially unmixed, and fordelivering said fresh gas and then 'a portion of said expired gas to thepatient.

16. In apparatus of the character described, means for receiving fromandre-delivering exhaled gas to a patient, and means for delivering freshgas to said patient, a substantial amount of said fresh gas beingdelivered to said patient substantially unmixed with said exhaled gasbefore said exhaled gas is re-delivered, said first mentioned meanscomprising a conduit having a cross section greater than 2.9 squarecentimeters and less than 12 square centimeters and having a capacitygreaterthan 600 cubic centimeters.

1'7. The method of administering gas, comprising removing andre-delivering exhaled gas, delivering fresh gas to the patient at thebeginning of the inspiration period of the breathing cycle before saidre-delivery.

18. The method of administering gas, comprising removing the tidalvolume of exhaled gas, adding to said volume a quantity of fresh gas,spilling from said volume an equal amount of expired gas, maintainingthe fresh and expired gases substantially undifiused in the resultantvolume, and delivering said resultant volume to the patient in such amanner that the fresh gas is inspired first.

19. The method of administering gas, comprising removing exhaled gas,adding fresh gas to said expired gas at a point proximal to the patient,spilling part of the expired gas distally from the patient, maintainingsaid gases substantially unmixed, and delivering said gases to thepatient, the fresh gas being delivered first.

20. The method of administering an anaesthetic gas to a patient,comprising allowing exhaled gas to be expired into a container, usingfresh gas to replace a certain amount of the exhaled gas during thequiet portion of the breathing cycle, and delivering to the patientfirst fresh gas and then the non-replaced exhaled gas, the fresh gas andthe said exhaled gas being delivered substantially unmixed from thecontainer to the patient.

21. The method of administering gas, comprising storingthe gas of anexhalation, interposing fresh gas in a conduit between the exhaled gasand the patient, and delivering to the patient the fresh gas followed bya portion of the stored gas of the preceding exhalation.

22. Apparatus of the character described,

comprising an enclosure formed with means adapted to fit over the faceof the patient, means to deliver a-controlled supply of gas to saidenclosure, and a conduit leading away from said enclosure, meansincluding said conduit providing a reservoir for exhaled gas, meansproviding an outlet at a distal point in said reservoir, said reservoirhaving a greater capacity than a single breath of the patient, and saidconduit having a sufficiently small cross-sectional area to prevent theready mixing of gases therein.

23. Apparatus of the character described, comprising an enclosure formedwith means adapted to fit over the face of the patient, means to delivera controlled supply of gas to said enclosure, and a conduit leading awayfrom said enclosure, means including said conduit providing a reservoirfor exhaled gas, means providing an outlet at a distal point in saidreservoir, said reservoir having a greater capacity than a single breathof the patient, said conduit having a suflilcient capacity to receivetheinflow of gas during the quiet period in the patients breath and havinginsuflicient cross-sectional area to permit any substantialintermingling of said introduced gas with the exhaled gas.

KARL CONNELL.

